Automatic rheostat.



PATENTED JULY 18, 1905.

G. J. STURGEON.

AUTOMATIC RHBOSTAT.

APPLICATION FILED FEB. 4. 1904.

Patented July 18, 1905.

PATENT OEEIoE.

CARSON J. STURGEON, OF ERIE, PENNSYLVANIA, ASSIGNOR TO FEDERAL ELECTRIC COMPANY, OF ERIE, PENNSYLVANIA, A CORPORATION PENNSYLVANIA.

AUTOMATIC RHEOSTAT.

v SPECIFICATION forming part of Letters Patent N0. 794,820, dated. July 18, 1905.

A plication filed February 4, 1904. Serial No. 191,960.

To all whom it may concern:

Be it known that I, CARsoN J. STURGEON, a citizen of the United States, residing at Erie, in the county of Erie and State of Pennsylvania, have invented certain new and useful Improvements in Automatic Rheostats; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters of reference marked thereon, forming part of this specification.

My invention relates to automatic rheostats, and particularly to automatic rheostats for starting electric motors and other electrical apparatus, in which the mechanism is operated automatically by the current to gradually cut out resistance-coils in circuit until the full volume of the current is admitted to the electric motor or other apparatus in circuit therewith. ln constructing this mechanism I utilize a solenoid provided with series coils in circuit with the electric motor or other 1 ally cut the resistance-coils out of circuit, and

mechanism connected therewith, which also operates to automatically cut out the shuntcoils of the solenoid when the lever and brush mechanism have nearly completed their traverse, and when the current is cut off from the rheostat the lever and brush mechanism are thereby released and automatically return to their normal position, turning in the resistance-coils and again closing the shunt-circuit, ready to be again operated as before. These features, together with certain constructive feature embodied in my invention, are hereinafter fully set forth and described, and illustrated diagrammatically in the accompanying drawings, in Which Figure l is a diagrammatic view of mechanism embodying my invention. Fig. 2 is a detail view of a section of the improved lever, brush, and contact-plate mechanism forming part of my invention. Fig. 3 is a sectional view of a modified construction of part of my invention. Fig. 4 is a detail of a portion thereof.

In the drawings thus illustrating my invention, A is a solenoid wound with a shunt-coil 'B and a series coil O. A is a soft-iron horseshoe-magnet on said solenoid A.

D is a lever operated by the plunger A of the solenoid A.

E is a dash-pot the piston-rod E of which is connected with the lever D.

F represents contactplates connected in circuit with resistance-coils G.

H represents an electric motor, I a cut-out switch, and i c" the positive and negative current supply lines.

The lever D is mounted on a stud J so as to swing freely thereon, and on the free end of. the lever D there is a yoke D, which embraces the contact-plates F. In the arms of this yoke D .there are openings d d, in which contact-blocks cl (1, preferably of carbon, are mounted so as to move freely therein toward and from the sides of the contact-plates F. To hold the contact-blocks cl 0? in contact with the opposite sides of the contact-plates F, I provide springs d 6Z2, which operate on the contact-blocks d d to retain them in close contact with the opposite sides of the contactplates F as they are moved over them, as is clearly illustrated in Fig. 2. This construction of the brush mechanism produces two results. One is to present large contact-surfaces to the'contact-plates F, and thus avoid any tendency to form arcs between them, and the other is that there being no side strain on the brush-lever D it swings perfectly freely upon its supporting-pivot J and avoids the friction thereon caused by the action of a spring-actuated bush-block acting against one side only of the contact-plates F.

On the axis J of the lever D, I pivot an arm J, which when the lever D is at its lowermost point of traverse, as shown in Fig. 1, is brought into contact with a small magnet K, wound with a shunt-coil B, connected directly in circuit with the shunt-coil B of the solenoid A. This contact of the arm J with the magnet K is effected by a stud d in the arm D, which contacts with the arm J and brings it into contact with the magnet K as the lever D reaches its lowermost point of traverse. On the hub D of the lever D there is another stud d*, which when the lever D nearly reaches the uppermost point of its traverse engages the lever J and moves it away from the magnet K and breaks the contact formed therewith, as is illustrated by dotted lines in Fig. 1.

Connected with the hub D and with the lever J there is a spring L, which operates after the said contact is broken to retain the arm J out of contact with the magnet K until the stud cl", acting upon the arm J during the descent of the lever D, forces the arm J back into actual contact with the magnet K.

In lieu of the magnet-contact K (shown in Fig. 1) I can, if desired, use a modified construction of the shunt-coil contact mechanism, as illustrated in Figs. 3 and 4, in which a spring-contact K operates to engage the arm and a is the same in its constructionand operation as shown and described in Fig. 1.

On the hub D of the lever D there is a contact-brush M, which when the current passes from the line through the switch 1 and line 0 to the series coils (J of the solenoid A, from whence it passes through the line 0 to the brush M and hub D of the lever D, where a small portion of the current is shunted through the arm J to the magnet K and thence through the shunt magnet-coils B and line b to the shunt-coils B of the solenoid A and therefrom through the line Z) to the switch 1 and line 2", the remainder of the current passing from the lever-hub D", through the lever D and the brush D thereon, to the contactplates F and through resistance-coils G toline N, leading to the motor H, and thence by line a to the switch I and line 2".

In operation when the current is turned into the rheostat it passes through both the series and shunt coils of the solenoid, and by the joint action of said coils upon the solenoid A and the magnet A, embracing said solenoid, the plunger A of the solenoid A is raised, which raises the lever D, pivoted thereto, and

carries the brush mechanism D thereon over the contact-plates F, (the dash-pot mechanism E E retarding said movement, so as to cause the lever D to move slowly,) and thereby gradually cuts out all of the resistancecoils G, and as the lever D nearly reaches the uppermost point of its traverse the stud (Z thereon'moves the arm J back out of contact with the magnet K or away from the contact K when the form of contact shown in Figs. 3and 4 is used, as the case may be, thereby breaking the shunt-circuit and leaving only the series coils C to energize the solenoid, which, however, retains sui'ficient power therefrom to retain the lever D in its uppermost position until the current is cut off from the rheostat, when the lever D returns by gravity to its normal position, with the shuntcircuit arm J in contact with the magnet K or contact K, as the case may be, as illustrated in Figs. 1 and 2, ready again to be actuated by turning the current into the rheostat. It will thus be observed that I use a solenoid having both series and shunt coils in circuit when necessary to energize the solenoid, yet when the work of the solenoid is accomplished the shunt-circuit is cut out, leaving only the energizing effect of the series coils thereon when the series coils are carrying the maximum amount of current after the resistance has been cut out of the line, thereby avoiding any and all inductive effect that might interfere with the return movement of the lever and brush mechanism. It will also be seen that the mechanism is so constructed that it presents a large and constant contact surface to both sides of the contact-plates, and thereby prevents arcing and other dc structive action upon the brushes and contact-plates.

Having thus shown and described my invention so as to enable others to construct and use the same, what I claim as new, and desire to secure by Letters Patent of the United States, 1s

1. In an automatic rheostat the combination of a solenoid, series and shunt coils thereon, lever and brush mechanism in circuit with said series coils, operated in one direction by said solenoid, and mechanism operating automatically to out the shunt coils out of circuit as the lever and brush mechanism nears the end of its traverse in one direction, and to automatically close the shunt-circuit as the lever and brush mechanism reaches the end of its traverse in the opposite direction, substantially as set forth.

2. In an automatic rheostat, the combination of a solenoid, series and shunt coils thercon, a horseshoe-magnet embracing the solenoid, lever and brush mechanism in circuit with said series coils and connected with the plunger of said solenoid so as to be operated thereby, and mechanism operated by said lever to automatically cut out the shunt-coils of the solenoid as the lever and brush mechanism nears the end of its traverse in one direction, and to automatically close the shunt-circuit as the lever and brush mechanism reaches the end of its traverse in the opposite direction, substantially as set forth.

3. In an automatic rheostat, the combination of a brush-lever, a solenoid, series and shunt windings on said solenoid with said series coils in circuit with the brush-lever, a

contact-arm pivoted on the axis of the brushlever and forming part of the shunt-circuit, a contact mechanism in said shunt circuit with which said arm is adapted to contact, and means on the brush-lever for moving said contact-arm away from said contact mechanism as the brush-lever nears the end of its traverse in one direction, mechanism for retaining said contact-arm out of contact with the shunt-circuit contact mechanism after the brush-lever has completed its traverse in one direction and until it nears the end of its traverse in the opposite direction, and means on the brush-lever for then closing the contactarm against the shunt-circuit contact mechanism, substantially as set forth.

4:. In an automatic rheostat the combination of a series of resistance-coils, contactplates connected therewith, lever and brush mechanism adapted to be moved over said contact-plates, a solenoid for operating said lever and brush mechanism, series and shunt coils on said solenoid with said series coils in circuit with said lever and brush mechanism, mechanism for cutting out said shunt-circuit as the lever and brush mechanism nears the end of its traverse in one direction and for ed with resistance-coils, a yoke on the free end of said lever embracing the contact-plates, contact-blocks supported and movable in the arms of said yoke and adapted to contact with the opposite sides of the contact-plates, and spring mechanism on said yoke engaging the contact-blocks and operating to retain them in contact with the opposite sides of the contact-plates, substantially as set forth.

6. In an automatic rheostat for starting electric motors, a resistance arranged in the armature-circuit of a motor, a series of contact-surfaces connected therewith, a solenoid, shunt-coils thereon, a brush-lever operated in one direction by said solenoid over said contact-surfaces, electromagnetic means permanently in series with the armature-circuit of the motor for retaining the brush-lever in the position to which it is moved by the solenoid so long as cur-rent is passing through the m0- tor-armature circuit, and switch mechanism operating automatically to cut the shunt-coils of the solenoidout of circuit as the brush-lever nears the end of its traverse in the direction it is moved by the solenoid, and to automatically close said-solenoid shunt-circuit when the brush-lever reaches the end of its traverse in the opposite direction, substantially as set forth. a

In testimony whereof I aflix my signature in presence of two witnesses.

CARSON J. STURGEON.

Witnesses:

H. M. STURGEON, F. J. BASSETT. 

